This proposal describes methods for investigating ligand clustering effects at the cell-substrate interface from the standpoint of cell adhesion strength. The hypothesis is that small, dense ligand clusters will enhance cell adhesion strength compared to large, sparse clusters. This prediction is based on more general observations that clustering of ligands on biomimetic surfaces enhances cell adhesion and migration noted recently. The present work aims to extend the rigor with which these effects can be quantified by using novel surface chemistry approaches to preparing biomimetic substrates. These interfaces will be used in turn to assay cell adhesion strength as a discrete function of cluster size and local density.